Objective: The aim was to compare various pre-and post-operative parameters and to identify the predictors of mortality in neonates, infants, and older children undergoing Modified Blalock Taussig shunt (MBTS). Materials and Methods: Medical records of 134 children who underwent MBTS over a period of 2 years through thoracotomy were reviewed. Children were divided into three groups-neonates, infants, and older children. For analysis, various pre-and post-operative variables were recorded, including complications and mortality. Results: The increase in PaO 2 and SaO 2 levels after surgery was similar and statistically significant in all the three groups. The requirement of adrenaline, duration of ventilation and mortality was significantly higher in neonates. The overall mortality and infant mortality was 4.5% and 8%, respectively. Conclusion: Neonates are at increased risk of complications and mortality compared with older children. Age (6 ml/kg, mechanical ventilation >24 h and post shunt increase in PaO 2 (P Diff )